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To: Johannes Erdfelt <johannes@erdfelt.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org
Subject: Re: Determine if card is in 32 or 64 bit PCI slot?
In-Reply-To: <20010808161703.Q21901@sventech.com> <E15UaNj-00062K-00@the-village.bc.nu> <20010808165919.R21901@sventech.com>
From: Jes Sorensen <jes@sunsite.dk>
Date: 14 Aug 2001 17:55:57 +0200
In-Reply-To: Johannes Erdfelt's message of "Wed, 8 Aug 2001 16:59:19 -0400"
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>>>>> "Johannes" == Johannes Erdfelt <johannes@erdfelt.com> writes:

Johannes> On Wed, Aug 08, 2001, Alan Cox <alan@lxorguk.ukuu.org.uk>
Johannes> wrote:
>> Are you sure the card actually needs this. Most such cards support
>> dual address cycle, so when placed in a 32bit slot will still do
>> 64bit DMA

Johannes> No I don't know if it's needed. I had no idea that PCI could
Johannes> do that.

Johannes> Is dual address cycle mandated by the PCI specs?

According to the PCI spec "The master is required in all cases to use
two clocks to communicate a 64-bit address, since the width of a
target's bus is not known during the address phase."

Aka, the answer to your question is yes.

Jes